For the first time in 9 years, a large number of investigators with major interests in somatic cell genetics will meet in order to systematically assess the current evidence regarding various mechanisms by which the heredity of somatic cells can be altered. A major specific task will be to critically evaluate the evidence supporting a genetic vs. an epigenetic basis for certain classes of heritable variants observed in mammalian cell cultures. The proposed conference is one of a series of Gordon Research Conferences sponsored by a group of investigators whose major orientation has been in cellular and molecular pathology. At this 1974 conference, however, the participants will consider the desirability of initiating a new series of Gordon Conferences devoted to the discipline of somatic cell genetics; this field promises to play an increasingly important role in biomedical research.